Many of you may have experience with a rattling pump that sounds
like it might be churning rocks! Pump cavitation - a predominant
condition in centrifugal pumps - is the likeliest cause for
unusually noisy and excessively vibrating pumps.

Cavitation affects a pump's operating flow and pressure, thereby
having a significant impact on its performance and energy consumption.
It can damage a pump's impeller, bearings and other components,
and cause untimely mechanical failure of the entire pumping
system.

Cavitation is when gas bubbles or cavities form and subsequently
implode in the liquid in a pump's relatively low-pressure areas.
These bubbles are formed when the liquid's pressure dips below
the vapour pressure in the eye of the impeller. They take up
space around the impeller. This causes the pump to spend more
energy on dealing the bubbles, rather than on pumping liquid.
The resulting noise and vibration are formed by the implosion
of these bubbles.

Pump cavitation usually arises out of a difference between
the Net Positive Suction Head Available (NSPHa) and the Net
Positive Suction Head Required (NPSHr). NPSHa is a measure of
the resulting drop in pressure as liquid travels from the suction
nozzle to the impeller. NPSHr is the minimum net positive suction
head required to avoid cavitation.

Pump cavitation is typically symptomatic of:

1. Pressure imbalances and fluctuated flow rates created by
blockages in the suction or discharge sides of the pumping system;
2. Increase in temperature of pumped liquid, causing a drop
in operating pressure;
3. Faulty pipe design or improper pump sizing.

How can it be prevented?

With careful planning and monitoring, pump cavitation can be
avoided. Here's how:

Choose the right design: The best way to avoid cavitation
is to get your pumping design system right! While designing
the pumping system and choosing the pump size, it is imperative
that NPSH is taken into consideration. If there is insufficient
NPSHa, this would be the best stage to catch it. Avoid sharp
bends, curves, and obstructions in your designs that can increase
frictional pressure loss and cause low pump suction pressure.

Re-evaluate design: If your pumping system is already
in place, it would be wise to explore options to increase NPSHa
by raising the liquid level in the suction head or using a booster
pump. Frictional losses in the pipework can be reduced by using
larger diameter pipes or less fittings. Precautions should also
be taken against excess turbulence in the suction line. However,
these measures are often impractical due to space and cost constraints.

Check pump efficiency: Ensure your pump is operating
at its best efficiency point by installing pressure gauges and
flow meters.

Monitor and Maintain: There's no compromising on this
prevention technique. It's always better to check filters and
strainers at regular intervals to ensure there are no clogs
or leaks in the pumping system. Condition Monitoring Technology
and automatic self-cleaning filters can also help protect against
cavitation. Keep an eye on the liquid's temperature to avoid
vaporization.

For more information on how to prevent pump cavitation or for
information on other industrial equipment to suit your needs,
call our toll-free number 1-800-367-4180. We have experts on
hand to help you choose, install, and maintain a variety of
equipment.

Pumps And Related Liquid Handling Equipment

About Us

Vissers Sales Corp. is a Canadian distributor and representative for liquid handling equipment related to the Chemical/Industrial market. We specialize in all types of pumps, mixers, valves, process controls, level and flow controls.